Electronic plumbing fixture fittings are known in the art. The commonly owned '110 patent discloses exemplary electronic plumbing fixture fittings.
Most automatic touchless faucets with optical sensors operate based on the principle that the light emitted from a transmitter is reflected from an object and returns to the receiver, and the water is turned on if the received signal exceeds a certain trigger level. Commonly, in order to have a consistent and repeatable triggering, complex algorithms for improved rejection of false positive or false negative are employed beyond setting a simple trigger level. However, the signal level of the reflected light traveling back to the receiver is affected by the reflectivity of the object—i.e., the color, texture, glossiness, transparency, and size of the object affect how much the light reflects and returns to the receiver.